In general, in the case of performing a dumping work that is one of excavating works of an excavator, an upper swing structure may swing up to a dumping position to load a loading container of a dump truck with excavated earth and sand after a digging work is completed. That is, joysticks of swing and boom-up of the upper swing structure may be operated almost simultaneously to adjust a swing angle and a boom-up height to reach a dumping position.
In this case, since an operator simultaneously determines the dumping position and dumping height while operating the swing joystick with one hand and operating the boom-up joystick with the other hand, it is required for the operator to pay much attention thereto. In other words, the operator should pay careful attention in operating the swing joystick to make the excavated earth and sand reach the dumping position and simultaneously operating the boom-up joystick to match the dumping height to the loading container.
As an example, if the dumping position gets out of an operator's viewing angle, the operator may accurately match the dumping position only in the case where the dumping position comes into the operator's viewing angle through performing of somewhat swing driving.
As described above, in order to perform the above-described works to match the swing angle and the boom-up height during the dumping work, operator's concentration is required in separately operating the swing joystick and the boom joystick while confirming the dumping position, and thus operator's fatigue is increased.
Further, if the dumping height does not match the loading container during the dumping work, it is required for the operator to match the dumping height again through the operation of the boom-up joystick, and this may cause the increase of the work time to deteriorate the work efficiency.